Could anybody help me in my problem?
Some time ago I finished my attic. I put plastic vent channels next to the roof, then put insulation (vapor barrier towards inside). Now with this cold weather, the whole insulation is soaked with water, and particularly next to the plastic vent channels (where it is most cold). I guess it is condensation. I have soffit vents and no ridge vent, but I guess during the winter it would not help anyway. Can anybody tell me what I can do?
Thanks,
Dmitriy Reznik

concretemasonry

01-29-2007 11:53 AM

Water in the insulation

It appears you have no ventilation and any moisture can condense and accumulate.

Your soffit vents will not work unless you have vents near or on the ridge. - There is no way for the air to circulate, so the water wilcondense on any cold surface.

redline

01-29-2007 11:55 AM

No ridge vent?
Do you have any other type of vent near the top of the roof?

dpreznik

01-29-2007 12:44 PM

No, I have nothing at the top, only soffit vents.
But I wonder how cold air flow can help avoid condensation on the opposit side of the vent channel? We still have there warm air meeting the cold surface of the vent channel, don't we?

concretemasonry

01-29-2007 02:46 PM

Water in the insulation

The top vent carries the moist air out of the venting area.

Where did you put your insulation? - Not against the roof I hope.

You MUST have an air flow under your roof sheathing to exhaust the moisture. I would also check for ways moisture could be getting into your attic. - Do you have a vapor barrier to keep the moisture inside the house?

dpreznik

01-29-2007 02:56 PM

Thank you very much for the answer.

Quote:

Originally Posted by concretemasonry
(Post 31645)

The top vent carries the moist air out of the venting area.

How is that? The air would go from the soffit vent through the vent channel to the ridge vent. The moisture is separated from the air flow by the plastic vent channel.

Quote:

Originally Posted by concretemasonry
(Post 31645)

Where did you put your insulation? - Not against the roof I hope.

The insulation is against the vent channel which is against the roof. So there is a space between the roof and the insulation.

Quote:

Originally Posted by concretemasonry
(Post 31645)

You MUST have an air flow under your roof sheathing to exhaust the moisture.

I just don't get how the moisture would be exhausted if it is separated from the air flow by the plastic of the vent channel.

Quote:

Originally Posted by concretemasonry
(Post 31645)

I would also check for ways moisture could be getting into your attic. - Do you have a vapor barrier to keep the moisture inside the house?

Yes, I use insulation with vapor barrier paper on it, but it is not complete barrier, of course.

concretemasonry

01-29-2007 03:19 PM

You said you have no ridge vent so there is no ventilation and circulation!!

Your soffit vents are doing nothing and the moisture is accumulating somewhere and is trapped in the fiberglass, which does a wonderful job of holding it.

dpreznik

01-29-2007 03:59 PM

Quote:

Originally Posted by concretemasonry
(Post 31654)

You said you have no ridge vent so there is no ventilation and circulation!!

Your soffit vents are doing nothing and the moisture is accumulating somewhere and is trapped in the fiberglass, which does a wonderful job of holding it.

But if even I had the ridge vent, how would the moisture penetrate through the plastic of the vent channels to get to the ridge vent?

concretemasonry

01-29-2007 04:18 PM

Water in the insulation

The chutes are not meant to be vapor barriers. They are just a friction piece of foam or cardboard. Their purpose is to provide an open area for the ventilation from the soffit vents up through the ridge or roof vents. By not having roof vents, you are stopping ventilation.

You already recognize that the minimal vapor barriers on fiberglass or poly film is not perfect. You also have some leakage from your house upward through cracks and around your access hatch or doorway. The ventilation is to remove the warmer humid air rather that let it condense on a cool surface.

It is possible to insulate the underside of your roof, but I am sure you do not want that expense (unless you own or a promoting some kind of foam) and all the other sealing requirements.

dpreznik

01-29-2007 04:36 PM

Quote:

Originally Posted by concretemasonry
(Post 31660)

The chutes are not meant to be vapor barriers. They are just a friction piece of foam or cardboard. Their purpose is to provide an open area for the ventilation from the soffit vents up through the ridge or roof vents. By not having roof vents, you are stopping ventilation.

I understand that those things were not intended to be vapor barriers. But because in my case they are made of plastic, they actually are barriers. So I don't understand how would the moisture penetrate through it even if I had the ridge vent? Maybe it was wrong to install plastic vent channels?

concretemasonry

01-29-2007 05:06 PM

Water in the insulation

Of course they might stop some vapor, but the are either stapled or friction fit with cracks. There is no seal and none is intended.

You violated the critical ventilation rule and do not have any roof vents and that is the major problem. Correct that and then see if there is anything else to address.

Post photos so we can see what other problems there might be.

dpreznik

01-30-2007 06:52 AM

Thank you very much for your help.

redline

01-30-2007 08:40 AM

Why was a ridge vent not installed after you went to the effort to put in the baffles?

Now you have to install the ridge vent, remove the wet insulation, replace the insulation and/or drywall...

dpreznik

01-30-2007 09:54 AM

Quote:

Originally Posted by redline
(Post 31718)

Why was a ridge vent not installed after you went to the effort to put in the baffles?

Now you have to install the ridge vent, remove the wet insulation, replace the insulation and/or drywall...

I didn't think it was necessary. Also, I did everything myself, and I would not be able to install ridge vent. I am afraid of heights.

Don't you think the wet insulation can dry up by inself if I install the ridge vent?

concretemasonry

01-30-2007 12:16 PM

Water in the insulation

You will have to put in some kind of roof ventilation.

Your fiberglass will not dry out enough in place to perform efficiently. As little as 1/2 to 1% moisture can have an effect.

Fiberglass does not absorb moisture but it will hold water. Dues to insulating concept of "dead" air spaces, you will not get enough circulation to dry it out while it is in place. Since you should remove it, you would be better off to just replace with new, rather than try to COMPLETELY dry out the old.